1. Field of the Invention
This invention relates generally to toilet flush valves and, more specifically, to valves providing alternative flush water volumes,
2. Discussion of the Prior Art
Toilets typically include a bowl which is adapted to receive liquid and solid waste, and a tank which provides a reservoir of water for flushing the waste from the bowl. Apparatus which is commonly mounted in the tank includes a flush valve assembly which is operable by the user to initiate the flushing of the bowl. A fill valve is also commonly mounted in the tank to refill the tank with a predetermined amount of water to be used in the next flushing operation.
Flush valve assemblies can vary considerably in their complexity, but typically include a flush valve, a float and an actuation mechanism. By operation of the actuation mechanism, the flush valve opens to release water from the tank into the bowl and closes when the float reaches a predetermined level indicative of the amount of water left in the tank.
More complex flush valve assemblies, such as that disclosed in PCT application number WO9502738 provide alternative flush water volumes. Prior to initiating the flushing operation, the user chooses between a large flush water volume for solid waste, and a smaller flush water volume for liquid waste. In the past, this selection has been made by a mechanical switch assessible to the user from outside the tank. Once the selection has been made, the associated flushing operation is initiated by operation of a pull tab also assessible from outside the tank.
These dual-flush toilet valves commonly include a selection apparatus which is mounted to the top of the tank, and a flush valve which is mounted to the bottom of the tank. With this design it is often desirable to adjust the axial distance separating the flush valve and the selection apparatus in order to accommodate tanks of various heights. In the past, this axial adjustability was provided by a shaft extending from the selector apparatus downwardly toward the flush valve. The length of this shaft had to be determined and the shaft cut to accommodate a particular height of the tank. This was a cumbersome procedure which had to be carried out with each installation. Unfortunately, once the shaft was cut, the valve assembly was rendered useless for taller toilet tanks. Mounting has also been a problem in tanks having mounting holes slightly misaligned. There has been no radial adjustability in prior flush valves to accommodate these toilets.
Within the tank, a hollow float has been provided with a water inlet and an air outlet. Selection of the reduced flush water volume has provided a controlled release of air from the air outlet to atmospheric pressure. This structure has facilitated the passage of water into the hollow float thereby decreasing the buoyancy of the float during the flushing operation and prematurely closing the flush valve.
U.S. Pat. No. 5,228,144 discloses a structure for adjusting the flush volume by controlling a release of air from the hollow float into a pressure tube which extends into the water in the tank. This tube provides a variable pressure that is dependent upon the level of the water in the tank. By adjusting the level of the tube in the tank, the pressure can be varied to provide a predetermined but adjustable flush water volume.